1. Field of the Invention
The present invention relates to a process for the manufacture of flat precision parts such as masks, templates and the like, and more particularly to photolithographic methods for generation of such parts.
2. Description of the Prior Art
Masks, templates and the like having openings therein of the required small size and highly detailed contours with a thickness guaranteeing sufficient mechanical stability, can not be manufactured by conventional etching technology. A photolithographic technique is employed in the current art comprising the steps of generation of a photo resist structure on a metallic carrier, plating a metal on the carrier in the photo resist openings removing the metal-photo resist structure from the carrier, and stripping the photo resist from the metal.
The above described procedure is limited as to the fineness of detail which may be achieved by the resolution of the photo resist. The material thickness of the template produced is limited by the thickness of the photo resist. Thickness and resolution of the photo resist are chemically correlated in such a manner that taking steps to increase thickness of the photo resist decreases resolution and likewise increased resolution demands decreased photo resist thickness. A template requiring finely detailed openings thus cannot be produced with high material thickness, by the conventional means.
A further disadvantage of the known methods is that after exposing and developing the photo resist on the carrier, the uppermost portions of the photo resist are more intensively exposed resulting in a tapering of the resist from an upper widest point to a narrowest point where the resist meets the carrier. Apertures having a trapezoidal cross section are thus produced. Further, in the conventional process a small air gap always exists between the mask, which is not perfectly flat, and the resist. When dry photo resist is utilized, having a protective foil attached thereto, an additional distance between the mask and the resist is created.